(RHSA-2011:0356) Important: krb5 security update

Kerberos is a network authentication system which allows clients and
servers to authenticate to each other using symmetric encryption and a
trusted third-party, the Key Distribution Center (KDC). The Public Key
Cryptography for Initial Authentication in Kerberos (PKINIT) capability
provides support for using public-key authentication with Kerberos.

A double-free flaw was found in the way the MIT Kerberos KDC handled
initial authentication requests (AS-REQ), when the KDC was configured to
provide the PKINIT capability. A remote attacker could use this flaw to
cause the KDC daemon to abort by using a specially-crafted AS-REQ request.
(CVE-2011-0284)

All krb5 users should upgrade to these updated packages, which contain
a backported patch to correct this issue. After installing the updated
packages, the krb5kdc daemon will be restarted automatically.